Spring motor



Sept. w, 1940. R G. LE TOURNEAU SPRING MCIJTOR Filed June 4, 1938 INVENTOR R. G.Le1'0u1'1zeau BY Q ,m

. ATTORNEY Patented Sept. 10, 1940 UNITED STATES SPRING MOTOR Robert G. Le Tourneau, Peoria, 111., assignor to R. G. Le Tourneau, Inc.

Application June 4, 1938, Serial No. 211,861

3 Claims.

Thisinvention relates to spring motors and particularly represents improvements over the motor shown in my Patent No. 2,119,335, dated May 31, 1938.

The spring motor of the present invention, like the previous one, is especially designed for use on a scraper such as that shown in my Patent No. 2,112,105, to control the retracting or return movement of the tailgate of the scraper. In the original structure, advancing of the tailgate placed the return spring under an ever-increasing tension with the aid of an ever-increasing leverage.

The object of the present invention .is to improve the construction of the spring motor so that a greater variation or increase in the leverage is obtained when most necessary, which is when the spring is becoming highly tensioned or compressed, and is correspondingly hard to manipulate.

At the same time, great simplicity of construction is retained, and the present structure occupies no more space than the previous one.

In the drawing similar characters of reference indicate corresponding parts in the several views:

Figure 1 is a side elevation of my improved spring motor, as mounted in connection with the frame structure and tailgate of a scraper, showing the spring connected cable unwound from its spiral and the spring slack, and the tailgate cable wound onto its spiral and the tailgate retracted.

Figure 2 is an opposite side view of the spiral cable drum of the spring motor, but showing the tailgate cable unwound from its spiral as when the tailgate is advanced, and the spring cable wound onto its spiral as when the spring is compressed.

Figure 3 is a transverse section of the drum unit.

Referring now more particularly to the characters of reference on the drawing, the spring motor comprises a two-cable drum unit I, turnably mounted by an axial shaft 2 on the framework 3 of the scraper at the back and centrally of the width thereof.

The front side of the drum (considering Fig. 1) is formed as a spiral cable receiving face or groove 4, engaged by a cable 5 which extends forwardly to a connection with the tailgate 6 of the scraper. The spiral face is disposed so that it diverges 60 from the axis of the drum in a clockwise direction. The cable is anchored on the drum at the point of greatest diameter of the spiral, as indicated at l, and when the tailgate is retracted, the cable is wrapped about the groove for the II full length thereof and pays out from the small end of the spiral below the axis of the drum, as plainly shown in Fig. 1.

The opposite or back side of the drum is also formed as a cable receiving spiral 8, of the same extent as spiral 4, but diverging in a counterclockwise direction when looking at the side of the drum on which spiral 4 is disposed. In other words, the spirals are arranged in opposed relation to each other, and in actual manufacture, a pair of identical single-spiral members, set back to back, are used to form the drum unit.

A cable 9, anchored on the drum at the point of greatest diameter of spiral 9 as indicated at H), extends forwardly from said spiral above the drum axis and through a heavy helical compression spring I I This spring is enclosed within a beam l2 forming part of the framework of the scraper, and abuts at its rear end, or the end nearest the drum, against a hollow crossbeam I3 having openings through which the cable projects. At its head end, the spring is engaged by a cap plate M on which the forward end of the cable is anchored. The cable 9 is arranged on its spiral relative to cable 5 so that said cable 9 is unwinding from its spiral, and is paying out from the small toward the large end thereof, when the tailgate is being retracted and cable 5 is winding onto its spiral and is approaching the small end thereof. The spring I! is then practically slack, as shown in Fig. 1.

When the tailgate is pulled forward or advanced from its retracted position, the corresponding cable 5 gradually unwinds from its spiral, and in doing so of course imparts rotation to the drum unit. This causes the spring cable 9 to wind onto its spiral from the large end thereof. When the tailgate is fully advanced and the spring is fully compressed by the accompanying shortening of the cable 9 ahead of the drum therefore, said cable 9 is fully wound onto its spiral in a position to subsequently pay out from the small end of its spiral. At the same time, cable 5 is fully unwound from its spiral and is in position to subsequently wind onto its spiral from the large end thereof, as shown in Fig. 2.

The beam l2 and spring ll therein are preferably disposed relative to drumshaft 2 and spiral 8 so that the axis of the spring is substantially tangent to the spiral 8 at its small end. The cable thus extends straight from the small end of the spiral to the head end of the spring axially of the latter, giving a direct pull on the spring when most needed.

It will be obvious that the spiral 8 at its large end cannot also be tangent to the axis of the spring. In order therefore to enable the cable within the spring to always remain substantially alined with the axis thereof and avoid any possible binding of the cable against the spring or cross beam I3, I may mount a cable engaging roller l just back of the beam and above the cable. The cable is thus deflected somewhat from a straight line when the cable is engaging the larger portion of the spiral, but at the same time the compressing pull on the spring remains direct.

By reason of the above construction and arrangement of parts, it will be seen that with the initial advancing movement of the tailgate, a relatively great compressing movement is imparted to the spring by reason of the difference in leverage caused by the difference in radius of the corresponding portion of spirals 4 and 8.

As the tailgate advances, and the radius of spiral 4 at the point of pay-out of cable 5 increases, the corresponding radius of spiral 8 becomes decreased. A slower compressing movement of the spring accompanied by an increase in leverage to offset the resistance of the spring to such compression, is thus had. This decrease in spring movement and the increase in leverage take place in constant and inverse ratio until the tailgate is fully advanced.

From the foregoing description it will be readily seen that I have produced such a device as substantially fulfills the objects of the invention as set forth herein.

While this specification sets forth in detail the present and preferred construction of the device, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention, as defined by the appended claims.

Having thus described my invention, what I claim as new and useful and desire to secure by Letters Patent is:

1. A spring motor comprising a cable retaining spiral, a cable engaged with the spiral and anchored thereon at its large end, a spring connected to the cable and adapted to be loaded when the cable is wound onto the spiral, another cable retaining spiral fixed coaxially with the first spiral and disposed in reversed relation thereto, another cable engaged with said other spiral and anchored thereon at its large end, said other cable extending from its spiral for connection with an element adapted to be pulled away from the spiral whereby to then unwind said other cable from its spiral while rotating the latter; the cables extending in the same general direction but from opposite sides of the axis of the spirals, and being disposed on their spirals relative to each other so that when one cable is fully wound on its spiral and is then taking onto the small end thereof, the other cable is substantially fully unwound from its spiral and is then paying out from the large end thereof.

2. The combination with a scraper having a tailgate mounted for independent advancing movement from a normally retracted position; of a spring motor including a two drum unit having reverse spiral drums associated in relatively fixed coaxial relation, a pair of cables for said drums, each cable being secured at one end on the large end of the corresponding spiral drum, one cable being normally wound on its spiral drum and the other cable being normally unwound from its spiral drum, the other end of said one cable being connected with the tailgate, and a normally unloaded helical spring mounted on the scraper, the other end of said other cable being connected with said spring and arranged to load the latter upon winding of such other cable on its spiral drum.

3. In a spring motor, a drum having a cable retaining spiral, a cable secured at one end on the drum at the large end of and leading from the spiral whereby when the cable is fully wound on the spiral it will be taking onto the small end thereof, a helical compression spring mounted with its axis substantially tangent to the small end of the spiral, said spring being anchored at its end adjacent the drum and the cable extending axially through the spring to its opposite end, means connecting the cable and said opposite end of the spring, the latter being relatively slack when the cable is unwound from the spiral and a guide element for the cable between the drum and spring to maintain the cable within the spring in substantial axial alinement therewith.

ROBERT G. LE TOURNEAU. 

